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Enantioselective addition of diethylzinc to benzaldehyde over mesoporous SBA-15 functionalized with chiral proline derivatives

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Abstract.
Chiral proline derivative was anchored on mesoporous SBA-15 materials by nucleophilic substitution of
chloropropyl-functionalized SBA-15 with (S)-(-)-a,a-diphenyl-2-pyrrolidinemethanol. Chloropropylfunctionalized SBA-15 prepared by co-condensation of tetraethyl orthosilicate and 3-chloropropyltrimethoxysilane using P123 copolymer as the pore directing agent in strong acidic environment was found to lead to derivatives with chiral centers more homogeneously distributed in the mesopores than
that prepared by post-grafting. The resultant materials were very active and selective as catalysts in
enantioselective addition of diethylzinc to benzaldehyde to form (S)-1-phenyl-propanol with ca. 66% of
enantiometric excess (e.e.). The e.e. value was further improved to 75% by adding a small amount of n-
BuLi. The reaction rate and the enantioselectivity increased with the accessibility of the chiral proline
species in the mesopores and the hydrophobicity around the active sites. Moreover, the catalytic activity
was well retained after the used catalyst was regenerated by filtration, washing with 0.2 MHCl and then
neutralization by TMAOH.

Keywords: Asymmetric addition, Proline, Diethylzinc, Benzaldehyde, SBA-15, Mesoporous silica, Xe NMR

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Informasi Detail

Judul Seri

Applied Catalysis A: General

No. Panggil

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Penerbit

London : Elsevier B.V.., 2009

Deskripsi Fisik

Applied Catalysis A: General 359 (2009) 96–107

Bahasa

English

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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